Front-end thermal design methods 1

Why 2 Safety The risk for mistakes is dramatically reduced. Speed Re-designs delay product introduction. Cost 80% of the costs are fixed in the first 20% of the design process.

Front- and back-end tools 3 Front-end tools Provide overviews. Do not require detailed knowledge. Can cover many alternatives in a short time. Back-end tools Provide implementation proposals. Require detailed knowledge. Are aimed to make accurate calculations.

The cooling efficiency method 4 The cooling efficiency method estimates the maximum heat load that can be put on a PCB. The lay out impact is replaced by an experience value: “The cooling efficiency”. Typical outputExperience values

What is needed 5 An experience value for the cooling efficiency. (The right image on the former slide is a good start for telecom applications) A back end tool that provides experience values. (Btemp is currently the only thermal PCB tool on the market that displays the cooling efficiency) A temperature criterion. (The maximum allowed PCB temperature for the worst room temperature case) A PCB size. (Depth and height) A cooling arrangement. (Single or serially cooled PCBs) A front-end tool that employs the cooling efficiency concept. (For example Bload)  c =77%. Calculated by Btemp

The air efficiency method 6 The air efficiency method estimates the maximum heat load for PCBs with heat sinks. A good design should have an efficiency in the range 35% - 65%. Experience values Typical output

What is needed 7 An experience data bank for the air efficiency. (needs to be targeted for each specific application type) A back end tool that provides the air efficiency as an output. (Btemp is currently the only thermal PCB tool on the market that displays the air efficiency as an output) A temperature criterion. (The maximum allowed PCB temperature for the worst room temperature case) A PCB size. (Depth and height) A cooling arrangement. (Single or serially cooled PCBs) A front-end tool that employs the air efficiency concept. (For example Bload)  a =17% Calculated by Btemp

The thermal territory method 8 Layout applicationComponent application The thermal territory method estimates the surface that a component needs for its cooling. Thermal territories makes it easy to create good thermal layouts. The method can also be used as a front-end tool for components.

A software tool that supports thermal territories. (Btemp is one of the few software that can do this) A temperature criterion. (The maximum allowed PCB temperature for the worst room temperature case) Thermal properties for the PCB. (Thermal conductivity in the plate direction) A thermal component model. (Simple models are good enough) A cooling arrangement. (Single or serially cooled PCBs) What is needed 9

Conclusions 10 There are several thermal front-end methods. The tools needed are available, low cost and simple to use.